Thanks for your comments. My experience in this urban environment seems different. The warblers are very active and difficult to photograph well ( Panasonic Lumix). Most are flying in and out of a Chinese Elm catching small caterpillars in the air. Only when they stop to drink do I have a chance of a shot. Oddly, last year, the easiest to catch in my yard were the Northern Waterthrushes and Ovenbirds which fed on the ground mostly. Haven't seen any this year so far.